The present invention relates generally to measuring the concentration of gases and/or vapor in a sample and more particularly to measuring the concentration of carbon dioxide and water vapor in the air.
One type of gas analyzer utilizes a light source that projects a beam of light through a sample and a detector to detect the light after passing through the sample. These gas analyzers typically use a combination of sample filters and a single reference filter to analyze certain wave lengths of light. The concentrations of gases in the sample can be determined by examining the degree to which the certain wave lengths of light are absorbed by the sample. However, by using a single reference filter in conjunction with two or more sample filters, the accuracy of the measurements associated with the two sample filters may be decreased. In this analyzer, the filters are typically placed between the sample and the detector. However, this placement of the filters in relation to the source may render the analyzer more susceptible to drift, artifacts, and the like, which may reduce the accuracy of the analyzer.
Further, to measure the concentrations of gases in air, one type of gas analyzer utilizes an open air measuring chamber. This type of analyzer typically includes a source that produces light, a detector to receive the light, an a pair of mirrors that reflect the light to direct it from the source to the detector. When these mirrors are used in an open air measuring chamber, they are exposed to the environment and are subject to contamination that can effect the accuracy of the analyzer. Therefore, an analyzer that overcomes these deficiencies is needed.